Deposition of Gd2O3 Coatings by Reactive Anodic Evaporation in a Low-Pressure Arc

Abstract

Gd₂O₃ coatings are deposited at a rate of 1.6 μm/h using the reactive anodic evaporation of Gd from a water-cooled crucible in a discharge with a self-heated hollow cathode. A power density on the crucible surface (more than 0.5 kW/cm²) sufficient to evaporate Gd is achieved by increasing the discharge current to 30 A and compressing the electron flow in the anode region by the field of a short solenoid, the maximum induction of which is 20 mT. The composition of the gas–metal (Ar/O₂–Gd) plasma is studied using optical emission spectroscopy. It is shown that the high frequency of interaction of electrons with Gd vapor near the surface of the crucible provides an increase in the degree of metal ionization to ~90%; the degree of O₂ dissociation is ~13%. The structural and phase state of Gd₂O₃ coatings deposited at temperatures in the range from 150 to 600°C is studied. It is established that reactive anodic evaporation in a low-pressure arc (0.2 Pa) under conditions of an increased degree of ionization of the metal and reactive gas allows implementation of the low-temperature (150°C) formation of single-phase Gd₂O₃ coatings with a cubic structure, the level of internal stresses in which is ~0.1 GPa. A low level of internal stresses and synthesis temperature make it possible to obtain single-phase adhesively strong coatings with a thickness of ~1 μm.